Tow line switch

ABSTRACT

A switch for an in-floor towing system, the switch utilizing a sensor and a responder or switchplate, and a mechanical linkage interconnecting the sensor with the responder. The linkage includes a motion translating mechanism whereby rotational motion in one plane is converted into rotational motion in a plane at right angles thereto. The responder is mounted for rotation in the latter plane, and has a slot with walls such that in one position it provides a wall inclined crosswise to the main track and in another position provides a straight wall in one side of the main track closing off the spur track.

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Krammer 1 1 ay 30, 1972 54] TOW LINE STCH 3,388,674 6/1968 Dorrance ..104/130 736,197 8/1903 Bentz ..104/88 72 I enter: Robert K e F t M h. 1 rammg 2,840,005 6/1958 Henderson ..104/101 [73] Assignee: Rapistan Incorporated, Grand Rapids,

Mich. Primary ExaminerJames B. Marbert [22] Filed: Mar. 16 1970 Assistant Exa mineP-D. W. Keen Attorney-Price, Heneveld, Hulzenga & Cooper [21] Appl. No.: 19,993

[57] ABSTRACT [52] US. Cl. ..104/l30, 104/96, 104/172 ET A Switch f an i fl towing System the Switch utilizing a [51] Int. Cl. ..B6ll 13/02, EOlb 7/14 Sensor and a responder switchplate, and a mechanical ]ink [58] Fleld of Search ..lO4/88, 172 ET, 101, 96, 130; age interconnecting the Sensor m the responden The link 105/147; 246/431 age includes a motion translating mechanism whereby rotutional motion in one plane is converted into rotational motion [56] References cued in a plane at right angles thereto. The responder is mounted UNITED STATES PATENTS for rotation in the latter plane, and has slot with walls such that in one posltion it provides a wall inclined crosswlse to the 3,103,183 9/1963 Bradt 104/172 BT main track and in another position provides a Straight wall in 609,292 8/1898 one side of the main track closing off the spur track. 1,679,068 7/1928 Allen 884,383 4/1908 Hauptman 104/ 101 18 Claims, 13 Drawing Figures Patented May 30, 1972 3,666,50

5 Sheets-Sheet J INVENTOR ROBERT KRAMMER ATTORNEYS Patented May 30, 1972 5 Sheets-Sheet 2 INVENTOR ROBERT KRAMMER M "i jl 7 m% A j ww ATTORNEYS Patented May 30, 1972 5 Sheets-Sheet 3 Patented May 30, 1972 wfiwm 5 Sheets-Sheet 4 A20 ma 35 I FIG. 10 //5' INV ENTOR ROBERT KRAMMER ATTORNEYS ,6 6 5 Patented May 30,1912 3 6 U Q 5 Sheets-Sheet v INVENTOR ROBERT KRAMMER BY PW WM H'vMWv QUOW L/ ATTORN EYS TOW LINE SWITCH BACKGROUND OF THE INVENTION In sub-floor or in-floor conveyor systems, chains are driven through in-floor tracks to tow vehicles by engaging a downwardly depending portion of the vehicle, such as a pin. In addition to main tracks, there are branch or spur tracks to which the vehicles must occasionally be switched. It is common practice to control the switches at the juncture of the branch and main tracks with automatic sensors which are triggered only by particular vehicles according to selector or actuator pins positioned on the vehicles. The sensors then shift the switch plate or responder to divert the vehicle to the branch track if the vehicle triggers the sensor. One method of connecting the sensor to the responder is by means of a cable, the responder including a tongue vertically pivoted out into the path of the main track. An example of such a construction is disclosed in US. Pat. No. 3,316,856. This construction re lies upon a cable for the force transmittal. This invention provides a positive mechanical linkage between the sensor and the switch plate. Also, such construction generally utilizes a switch plate having a minimum of exposed surface which might be damaged by vehicles passing over it. This invention provides a switch having much superior structural capacity to withstand the weight of vehicles passing over it.

Another method of conveying or transmitting the signal force from the sensor to the responder is to utilize trip levers which are not interconnected but which abut one another so that when one is pulled by the sensor, the other is free to be pulled by a spring in a prescribed direction. An example of such a construction is disclosed in U.S. Pat. No. 3,26l,300. The difficulties with such a construction are that there is a lack of positive interconnecting engagement between the sensor and the responder, thereby subjecting the system to breakdown in the event one lever becomes improperly displaced with respect to the other.

SUMMARY OF THE INVENTION The invention relates to an in-floor conveyor system utilizing main and spur tracks for towing trucks over the floor. Specifically, the invention provides a switch for diverting such truck vehicles from a main track to a spur track, the switch including a sensor having a finger pivotally mounted for rotation about an axis at a right angle to the axis of the main track and a responder mounted so as to alternate between a retracted position and a diverting position at the junction of the spur track and the main track. The switch is characterized by the responder being mounted for rotation about an axis parallel to the main track, and by a mechanical linkage interconnecting the sensor to the responder so as to translate the rotation of the finger about its axis into rotation of the responder about its axis parallel to the track, whereby the responder is mechanically moved between the retracted and the diverting positions. The mechanical linkage includes a motion translation element secured to a shaft mounted coincident with the perpendicular axis for translating rotative motion of a sensor finger mounted on the shaft to a rotative motion in a plane at right angles to the axis of the track. The motion translation element and the mechanical interconnecting linkage causes the responder to shift from its retracted position to the diverting position. The responder itself features a generally pivotal barrel-shaped element with a slot in the curved sides thereof extending in the direction of the axis of rotation of the responder. The width of the slot varies along its length.

Accordingly, it is an object of the invention to provide a switch characterized by a linkage from the sensor to the responder which is positively interconnected so as to be generally free from the likelihood of breakdown.

It is a related object of the invention to provide a switch of the above character wherein the responder exposes a small surface area to the floor and to objects traveling thereacross.

Other objects and advantages will become apparent upon reference to the following drawings and detailed discussion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a plan view of the switch constructed in accordance with the invention;

FIG. 2 is a sectional elevation view taken along the line 11-- II of FIG. 1;

FIG. 3 is a fragmentary sectional view taken along the line IIIIII of FIG. 2:

FIG. 4 is a sectional elevation view taken along the line IV- IV of FIG. 1;

FIG. 5 is a fragmentary sectional view taken along the line V-V of FIG. 1;

FIG. 6 is a fragmentary sectional elevation view taken along the line VIVI of FIG. 4;

FIG. 7 is a fragmentary sectional view taken along the line VIIVII of FIG. 6;

FIG 8 is a fragmentary, enlarged, sectional elevation view taken along the line VIIIVIII of FIG. 1;

FIG. 9 is a sectional view similar to FIG. 8 but illustrating the responder shifted to its diverting position;

FIG. 10 is a fragmentary plan view similar to FIG. I but illustrating the responder shifted to its diverting position;

FIG. 11 is a fragmentary schematic view illustrating the operational positions of the sensor finger and the motion translating cam;

FIG. 12 is a fragmentary schematic plan view of the lock and release mechanism for the switch; and

FIG. 13 is a bottom view of the motion translating cam.

DESCRIPTION OF THE PREFERRED EMBODIMENT The invention relates to an in-floor or a sub-floor towing system utilizing a main track 20 and a spur or branch track 22 both positioned below the surface of a floor 24. A chain C1 (FIG. 4) is conventionally utilized to tow a truck vehicle across the surface of the floor 24 by engaging in downwardly depending pin 26 (FIGS. 1 and 8). The trucks generally utilize wheels 27 to move across the floor. A chain C2 (FIG. 4) separate from chain C1 conveys the pin 26 along the track 22, the spur or branch chain C2 entering the branch track 22 from a covered track 28. Normally, the spur chain C2 is slave driven from the main chain C1. Frequently no chain is provided in the spur track and this invention is not dependent upon the use of a chain in the spur track.

The track 20 may be any one of a number of conventional designs. For purposes of illustration in areas other than that of a switch or similar equipment, it consists of a shallow, U shaped channel 30 having a wear plate 31 at the bottom and a pair of top strips or guides 32 set flush with the floor and spaced to provide a pin receiving slot narrower than the channel. In the area of the switch the strips 32 are replaced by cover plates 33 also flush with the floor and defining a slot forming a continuation of the one formed by the strips 32.

A switch 40 used to divert the truck vehicle and truck pin 26 from the main track 20 to the spur track 22 comprises a detector or sensor 42, a responder or diverter 100, and a mechanical linkage interconnecting the sensor to the responder. As used throughout the application, the words interconnecting mechanical linkage mean a linkage which is interconnected at all points so as to transfer motion mechanically, which linkage is not capable of separation during the intended use of the switch. All the mechanisms of the switch 40 are generally confined within a sub-floor housing 41.

Referring to FIGS. 1, 4 and 5, the sensor 42 comprises a finger 44 keyed to a rotatable shaft 70, the finger being spring biased in a clockwise direction, FIG. 5, by a finger tension spring 67. The finger is also designed to engage a truck mounted, downwardly depending selector or actuator pin 66 positioned to trigger the sensor as the truck passes thereover (FIG. 11). The finger projects up through a floor plate 50 flush with the floor having guards 51 on both sides of the plane of rotation of the finger 44. The guards are spaced to form a slot 48 through which the pin passes (FIG. I). Preferably, the slot 48 has an enlarged entrance at 49. The guards 51 are mounted on the floor plate 50. The guards 51 are convex to rovide a smoothly rounded, somewhat hemispherical projection. The platform is supported by a pillar 52 (FIGS. 4 and 6) which is floatingly mounted for vertical movement by two ears 58 upwardly biased by compression springs 60. The pillar 52 includes a bushing 54, the bushing 54 being slidably engaged on two sides by guide plates 56 (FIGS. 6 and 7). Bushing 54 mounts one end of the shaft 70.

It will be readily recognized that the function of the aforedescribed structure mounting the finger 44 is to allow the entire platform 50 together with the finger 44 and guards S1 to be depressed to the position shown in broken lines in FIG. 4 when a vehicle passes over the platform 50. Since vehicles of various types disassociated from the in-floor system normally pass over the system, this feature is important. This arrangement prevents damage to both the system and the vehicle. This depressibility feature insures that the finger 44 is actuated only by the appropriate selector pin and not unintentionally actuated by some other object.

The depressibility of the sensor unit is not in itself novel in this invention but the incorporation of this concept in a switch actuation mechanism which incorporates a shaft type connection rather than a flexible cable or electric connection is believed to be novel.

lnterconnecting Mechanical Linkage It will be recognized that the invention can be built both with and without the depressibility feature. The invention will first be described in a construction with the depressibility feature. This arrangement is best seen in FIG. 4.

To incorporate the depressibility feature, the finger actuated shaft 70 consists of two sections 70a and 70b joined by a universal joint 47. The shaft section 70a is rotatably supported by the stationary bearings 72 and between these bearings mounts the cam 78. The other end of the shaft 70b, as previously stated, is supported by the bushing 54.

Referring now to FIGS. 2, 4 and 5, a motion-translating cam 78 is mounted on the end of the shaft 70 remote from the universal for rotation with the shaft 70. The cam 78 features a track 80 in its lower face (FIG. 13) a portion of which spirals with respect to the axis of the shaft 70. The track is a groove recessed into the surface 82 of the cam 78. The track 80 traces 1 a path (FIG. 13) the end portions 85a and 85b of which are generally perpendicular to the axis of the shaft 70. Between these portions, a spiralling portion 850 is formed which advances axially along the shaft 70.

Engaged within the track 80 is a cam follower 86 shaped in the form ofa knob, the cam follower 86 being in turn mounted on the end ofa radial arm 90 projecting out and away from the end of a rotatable shaft 94 (FIGS. 2 and 5). The axis of shaft 94 is parallel to the track 20 and can be located, as shown, within a horizontal plane extending through the shaft 70. The shaft 94, in the illustrated embodiment, is mounted directly underneath the track 20. Keyed to the opposite end of the arm 90 is the responder or switch arm 100.

It will be readily appreciated that the rotational force transmitted by the finger 44 is at all times transmitted by structure of a relatively large cross-sectional area, particularly as contrasted with linkages utilizing cables. Thus, the structure is capable of sustaining substantial operating forces. Furthermore, it will be appreciated that the entire linkage is positively interconnected, thus eliminating the possibilities of breakdown due to the parts becoming disconnected.

The Switch Member Referring to FIGS. 1 and 8 through 10, in accordance with another aspect of the invention, the responder 100 features a barrel-shaped or hollow switch member 102 located in an opening 101 in the floor 24 at the juncture of the pin slot for the main and spur tracks. The switch member has a convex top 106. A slot 110 is located in the curved side 106 and extending lengthwise of the member from one end 112 of the switch member to the opposite end 114. The slot 110 is located opposite to the side 115 to which the shaft 94 is attached. The central opening in the switch member is of such size that the U-shaped portion of the track 20 passes through it with the top of the switch element positioned over the track. A narrowed portion 32a of one guard 32 passes through the switch member. This is opposite the opening to the spur track. A narrowed portion of the other guard extends into the switch member as the projection 32b. This projecting portion forms a guide for the truck pin 26 when the switch member 102 is shifted to diverting position and for this purpose has a rounded nose. The purpose of the guides 32a and 32b is to guide the pin 26 in lieu of sides 25 which are cut away at this point. The guides 32a and 32b cooperate with the switch member 102, guide 320 when it is open to the main track and guide 32!) when it is open to the spur track.

The slot is defined by sides and 122 which are spaced apart by a distance which varies from one end 112 of the element to the opposite end 114. Specifically. side 120 is gradually and progressively curved (FIG. 10) along a path which is askew to the axis of the element 102. The curvature of the side 120 is designed so that when the side 120 is shifted to the position illustrated in FIG. 10 the side 120 is seated across the track 20 forcing the truck pin 26 to divert to the spur track 22. In contrast, the side 122 of the slot 110 parallels the axis of the switch member 102. Thus, when the element 102 is rotated to the position illustrated in FIG. 9, the side 122 forms a continuation of the spur track side of the track 20, thus closing off access to the spur track 22 (FIG. 1).

Thus, it will be readily appreciated that at any one time, only a small portion of the switch member 102 is exposed at the floor surface. This reduces surface exposure significantly to lessen wear and damage from vehicles, not associated with the infloor tow system, passing over the switch. The construction of the switch member 102 is considerably stronger than that of the usual tongue type switch and thus substantially more resistent to damage from vehicles passing over it. Another significant fact of this switch element is the fact that, as contrasted with conventional tongue type switches, it permits a much smaller area of the switch to be exposed to traffic passing over it.

Switch Element Locking and Releasing Mechanism Referring now to FIGS. 1 through 3 and 12, it is necessary to reset the switch element after a truck pin 26 has been diverted to the spur track 22. Accordingly, a triggering dog is pivotally mounted to shift into the pin slot of the spur track 22. The dog 140 is mounted to the upper end ofa vertical shaft 142joumaled in brackets 144 and 146 (FIG. 3). The lower end of the shaft 142 mounts another dog 150 which is spring biased in a counterclockwise direction, as illustrated in FIG. 12, by a spring loaded ram 152. The spring biasing of the dog 150 urges the dog 140 outwardly into the pin slot of the spur track 22. A stop 154 limits the outward pivotal movement ofthe dog 150 and therefore ofthe dog 140.

A trip pawl is mounted on the end 161 of the shaft 94 (FIG. 2) on the side opposite the switch element 102 from the side mounting the radial arm 90. The pawl 160 is biased toward the dog 150 by a compression spring 162. Cooperating camming surfaces 164 and 166 are provided on the dog 150 and on the pawl 160, respectively. These camming surfaces provide a lock when the dog 150 and the pawl 160 occupy the position shown in FIG. 12 inasmuch as it is impossible for the pawl 160 to push the dog 150 out of the way so as to allow the pawl to occupy its original position shown in dotted lines 168. Thus, the engagement between the pawl and the dog forms a lock, the purpose of which will be described in detail under Operation." When the dog 140 is forced to rotate clockwise to the position shown in broken lines in FIG. 12, the dog 150 is forced past the cam surface 164 backing the pawl 160 against the spring 162 until the dog 150 has cleared the pawl. At that time, the spring 162 forces the pawl to return to the position shown in broken lines.

Operation Assuming the switch to be in normal position, that is, with the main track 20 open, as shown in FIG. 1, the sensing finger 44 is in its maximum position (A in FIG. 11) upstream of movement along the conveyor. When a selector pin 66, positioned to activate the switch approaches, it enters the slot 48 between the guards 51. As it passes through the slot it pivots the sensing finger 44 counterclockwise, as illustrated in FIG. 1 1. As it does so, it acts against the bias of the spring 67 (FIG. 5). This initial pivotal movement of the finger proceeds through a short are of travel which, by rotation of the shafts 46 and 70 and of the cam 78 mounted on the shaft 70, represents the distance traveled by the cam follower 86 in the straight track end portion 85a. Because portion 85a provides no axial movement of'the follower 86 with respect to the shaft 94, no rotational movement of the shaft 94 or the switch element 102 occurs. FIG. 1 1), the cam follower 86 begins to be engaged by the spiral portion 850 of the track 80, thereby causing the cam follower to move axially with respect to the shaft 46. This movement causes the shaft 94 to turn rotating the switch element 102 in a counterclockwise direction as shown in FIG. 8. This shifts the side 120 out over the track and into diverting position. During this movement, the dog 150 (FIG. 12) is locked in retracted position (shown in the dotted lines) by the extended pawl 160. However, when the sensing finger 44 has moved to position C (FIG. 1 1), the pawl 160 has been rotated sufficiently to permit the dog to pivot to extended position illustrated in solid lines in FIG. 12 under the bias of the ram 152. At this point, the switch element 102 has over-traveled beyond the point shown in FIG. 10, for reasons which will become apparent hereinafter and the cam follower 86 has entered the straight portion 85b of the track (FIG. 13). The sensing finger 44 is free to continue to pivot until it is flush with the floor (position D in FIG. 11). This pivotal movement has no rotational effect upon the shaft 94 because of the straight portion 85b of the track 80. The purpose of this overtravel is simply to accommodate selector pins which may hang down almost to the level of the floor, thereby preventing binding in the system. As soon as the finger 44 is released by the selector pin 66, the entire system rotates back an amount represented by the rotation of the pawl 160 from the position shown at the dotted line 170 to the position shown in solid line in FIG. 12. This arrangement accommodates both manufacturing tolerances and subsequent wear on the mechanism. It also permits a substantial variation in selector pin heights. When the switch element is seated in the position illustrated in FIG. 10, the truck pin 26 engages the wall or side 120 of the slot 110 causing the truck to be diverted to the spur track 22.

This invention provides an arrangement which positively assures shifting of the switch element 102 to diverting position before it is contacted by the truck pin. This avoids possible damage to both the truck pin or the switch element. Further, since the switch pin, upon being shifted to diverting position is locked in this position until after the truck pin has been diverted, the truck may be stopped while the pin is between the sensor and the switch element with the switch element remaining in diverting position until the truck has actually been diverted.

The truck pin 26 may impact the switch element with considerable force even though its rate of forward movement is relatively slow. Therefore, it is essential that the switch element be positively locked in diverting position. This is accomplished by the interengagement between the pawl 160 and the extended dog 150. So long as the dog 150 remains in the position illustrated in solid lines in FIG. 12 a positive lock is formed preventing either the springs 48 (FIG. 5) or 162 (FIG. 3) from rotating the shaft 94. Thus, the switch element is positively held in diverting position.

The pin 26 travels along the spur track until it cams against the dog 140 as shown in FIG. 12, causing the dogs 140 and 150 to rotate from the position shown in solid lines to the position shown in broken lines. This rotation, as previously described, releases the pawl 160, permitting the shaft 94 and the finger 44 to rotate back to their original positions. The pawl and shaft 94 are rotated by the spring biased ram 152, returning the switch element 102 to its retracted position shown in FIG. 1.

It will be recognized that this switch can be built without the depressibility of the sensor. In this case, the universal 47 is eliminated and the shaft 70 is a single piece mounting both the finger 44 and the cam 78. At the end of the shaft 70, adjacent the finger 44, a stationary bearing replaces the vertically movable one. The remainder of the structure is unchanged.

It will also be recognized that the functional and structural benefits of the rotatably mounted switch element 102 can be obtained without the specific mechanical linkage which has been described. Thus, the sensor could be associated with an electrical switch or a valve, either hydraulic or pneumatic, which when actuated, will activate a suitable power source for the switch element such as a solenoid or a power cylinder, either hydraulic or pneumatic which in turn would rock the shaft 94.

Although the invention has been disclosed in connection with a preferred embodiment, it will be readily apparent that alternate equivalent embodiments can be constructed within the scope of the invention. Accordingly, it is intended that these embodiments be included within the invention unless the temis of the following claims expressly state otherwise.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A switch to be mounted in a floor for an in-floor tow line conveyor having a main track and a spur track both opening through the floor to fonn a truck pin receiving slot, said switch mounted at the juncture between said main and spur tracks and having a truck pin engager, said pin engager comprising:

an element;

means mounting said element for rocking motion between retracted and extended positions about an axis parallel to said main track;

said element being shaped in the form of a hollow barrel encompassing said main track at said juncture and having an opening in its upper face generally parallel to its axis of rocking motion, one side of said opening being generally diagonal to said track;

said one side being offset laterally of said main track when said element is retracted and extending across said track when said element is extended to form a truck pin deflector communicating with said spur track;

a sensor;

means operatively connecting said sensor and said element for shifting said element between said positions;

means biasing said element into retracted position;

a release member operatively connected to said element and shifted into truck pin engaging position in the truck pin slot of said spur track simultaneously with the shifting of said element to extended position; and

a stop member locking said element in extended position, said stop member connected to said release member and shifting said stop member to non-locking position when said release member is engaged by a truck pin.

2. A switch as described in claim 1 wherein said opening in said element has a second side generally parallel to said main track; said second side forming a closure across the truck pin slot of said spur track when said element is in retracted position.

3. A switch as described in claim 1 wherein said means operatively connecting said sensor and said element includes a first shaft and a second shaft connected to said sensor and said element respectively; a motion translating element connecting said first shaft to said second shaft, said motion translating element including a cam fixedly mounted to one of said shafts and a cam follower fixedly mounted to the other of said shafts and engaged by said cam.

4. A switch for an in-fioor track and chain system for towing vehicles by engaging a downwardly depending portion thereof, said switch connecting a main track to a branch track and including both a sensor having an element mounted for pivotal movement parallel to said main track and a responder having a diverting member mounted so as to alternate between a retracted position and a diverting position at the junction of said branch track to said main track; said switch being characterized by said diverting member being pivotally mounted for rotation about an axis generally parallel to said main track; mechanical linkage means interconnecting said sensor to said responder so as to translate pivotal movement of said element into movement of said diverting member from one of its positions to the other, said linkage means including two shafts, one connected to and mounted for rotation by said element and the other connected to said diverting member and rotatably mounted for rocking said diverting member between its two positions, said other shaft being generally parallel to said main track; motion translating means for translating rotational motion about one of said shafts to rotational motion about the other of said shafts, said motion translating means including a cam fixedly mounted on one of said shafts and a cam follower fixedly mounted on the other of said shaft and engaged by said cam.

5. The switch as defined in claim 4, wherein said cam has a track which spirals along a portion of its surface axially and concentrically with respect to a portion of said shaft, said cam follower being engaged by said track whereby rotation of said one shaft causes said follower to move axially with respect to said one shaft.

6. The switch as defined in claim 5, wherein said cam track includes at both ends thereof, a lost-motion portion wherein motion of said cam results in no motion of said follower with respect to said one shaft.

7. The switch as defined in claim 5, wherein said other shaft includes an arm extending radially therefrom, said follower being fixed to the end of said arm, whereby axial movement of said follower with respect to said one shaft results in rotation of said other shaft.

8. The switch as defined in claim 4, wherein said diverting member is a generally barrel-shaped element with a slot in the curved sides thereof and extending from one end to the other of said element, the width of said slot varying from one end to the other of said diverting member.

9. The switch as defined in claim 8, wherein said shaft connected to said diverting member mounted coincident with said parallel axis, and said diverting member is attached to said shaft at the side of said diverting member opposite to said slot so as to mount said curved sides and said slot concentrically with respect to said shaft, whereby rotation of said shaft causes said curved sides and said slot to rotate about said parallel axis.

10. The switch as defined in claim 4, wherein said responder has means biasing said diverting member into retracted position and means for locking said diverting member in extended position and releasing it to return to its retracted position.

11. The switch as defined in claim 10, wherein said locking means includes a dog on one end of a rotatable shaft; a stop for engaging said dog when said diverting element is in diverting position; a pawl connected to said diverting element for pivotal movement therewith, and cooperative camming surfaces on said dog and said pawl, said surfaces when mated being especially adapted to press said dog against said stop and hold said pawl with said diverting member in diverting position.

12. A switch as defined in claim 4, wherein support means are provided for said sensor, said support means biasing said sensor into raised position above the floor surface and permitting said sensor to be depressed into said floor; a flexible connection in said one shaft permitting the end thereof connected to said sensor element to pivot with respect to the other end thereof.

13. A switch as defined in claim 12 wherein said flexible connection is between said sensor element and said motion translating means.

14. A switch as defined in claim 12 wherein said sensor has a pair of guards normally projecting above the floor surface and spaced to form a slot to receive said sensor element; said guards being depressible into the floor with said sensor.

15. A tow pin directing switch for the two pm guiding channel of a recessed in-floor conveyor at the juncture of a generally U-shaped main track guiding channel and a spur track guiding channel diverging therefrom, said main track having an opening in a side thereof with the juncture of said spur track, said switch comprising: a body element; said body element being shaped in the form of a hollow barrel encompassing said main track at said juncture; means mounting said body element for rocking movement laterally of said main track, said body element having an upwardly opening slot therein extending in the direction of said main track, one side of said slot being at an angle to said main track and converging toward the other side of said slot in the same direction as said guiding channel of said spur track diverges from the guiding channel of said main track, said slot forming a continuation of the guiding channel of said main track when said body element is rocked into one position and said one side of said slot extending across said guiding channel of said main track and the adjacent portion of said slot forming an angular guideway connecting said main and spur track guiding channels when said body element is rocked into the other of its positions.

16. The tow pin directing switch as defined in claim 15 wherein said body element is pivotally mounted for rocking movement on an axis generally parallel to said main track and said main'track passes through said element.

17. A switch as described in claim 15 wherein a sensor is provided; second means for imparting rocking motion to said element; said sensor being connected to said second means for shifting said element from retracted to extended position.

18. A switch as described in claim 19 wherein said element is biased into retracted position; a release member connected to said element and shifted into retracted position; a release member connected to said element and shifted into truck pin engaging position in the truck pin slot of said spur track simultaneously with the shifting of said element to extended position and a stop member locking said element in extended position; said stop member connected to said release member and shifting said stop member to non-locking position when said release member is engaged by a truck pin.

P0405) TED STATES PATENT OFFICE TIFICATE @F CORRECHON Patent No. 3 666 050 D d May 30, 1972 Inventor) Robert Krammer It is certified that error appeare in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2 line 35:

"in" should read a Column 5, line 12:

After "occurs" insert As the finger 44 approaches its vertical position (B in Signed and sealed this 31st day of October 1972.

(SEAL) Attest:

EDWARD MGFLETCHERJR. ROBERT GOT'I'SCHALK Attesting Officer Commissionerof Patents 

1. A switch to be mounted in a floor for an in-floor tow line conveyor having a main track and a spur track both opening through the floor to form a truck pin receiVing slot, said switch mounted at the juncture between said main and spur tracks and having a truck pin engager, said pin engager comprising: an element; means mounting said element for rocking motion between retracted and extended positions about an axis parallel to said main track; said element being shaped in the form of a hollow barrel encompassing said main track at said juncture and having an opening in its upper face generally parallel to its axis of rocking motion, one side of said opening being generally diagonal to said track; said one side being offset laterally of said main track when said element is retracted and extending across said track when said element is extended to form a truck pin deflector communicating with said spur track; a sensor; means operatively connecting said sensor and said element for shifting said element between said positions; means biasing said element into retracted position; a release member operatively connected to said element and shifted into truck pin engaging position in the truck pin slot of said spur track simultaneously with the shifting of said element to extended position; and a stop member locking said element in extended position, said stop member connected to said release member and shifting said stop member to non-locking position when said release member is engaged by a truck pin.
 2. A switch as described in claim 1 wherein said opening in said element has a second side generally parallel to said main track; said second side forming a closure across the truck pin slot of said spur track when said element is in retracted position.
 3. A switch as described in claim 1 wherein said means operatively connecting said sensor and said element includes a first shaft and a second shaft connected to said sensor and said element respectively; a motion translating element connecting said first shaft to said second shaft, said motion translating element including a cam fixedly mounted to one of said shafts and a cam follower fixedly mounted to the other of said shafts and engaged by said cam.
 4. A switch for an in-floor track and chain system for towing vehicles by engaging a downwardly depending portion thereof, said switch connecting a main track to a branch track and including both a sensor having an element mounted for pivotal movement parallel to said main track and a responder having a diverting member mounted so as to alternate between a retracted position and a diverting position at the junction of said branch track to said main track; said switch being characterized by said diverting member being pivotally mounted for rotation about an axis generally parallel to said main track; mechanical linkage means interconnecting said sensor to said responder so as to translate pivotal movement of said element into movement of said diverting member from one of its positions to the other, said linkage means including two shafts, one connected to and mounted for rotation by said element and the other connected to said diverting member and rotatably mounted for rocking said diverting member between its two positions, said other shaft being generally parallel to said main track; motion translating means for translating rotational motion about one of said shafts to rotational motion about the other of said shafts, said motion translating means including a cam fixedly mounted on one of said shafts and a cam follower fixedly mounted on the other of said shaft and engaged by said cam.
 5. The switch as defined in claim 4, wherein said cam has a track which spirals along a portion of its surface axially and concentrically with respect to a portion of said shaft, said cam follower being engaged by said track whereby rotation of said one shaft causes said follower to move axially with respect to said one shaft.
 6. The switch as defined in claim 5, wherein said cam track includes at both ends thereof, a lost-motion portion wherein motion of said cam results in no motion of said folloWer with respect to said one shaft.
 7. The switch as defined in claim 5, wherein said other shaft includes an arm extending radially therefrom, said follower being fixed to the end of said arm, whereby axial movement of said follower with respect to said one shaft results in rotation of said other shaft.
 8. The switch as defined in claim 4, wherein said diverting member is a generally barrel-shaped element with a slot in the curved sides thereof and extending from one end to the other of said element, the width of said slot varying from one end to the other of said diverting member.
 9. The switch as defined in claim 8, wherein said shaft connected to said diverting member mounted coincident with said parallel axis, and said diverting member is attached to said shaft at the side of said diverting member opposite to said slot so as to mount said curved sides and said slot concentrically with respect to said shaft, whereby rotation of said shaft causes said curved sides and said slot to rotate about said parallel axis.
 10. The switch as defined in claim 4, wherein said responder has means biasing said diverting member into retracted position and means for locking said diverting member in extended position and releasing it to return to its retracted position.
 11. The switch as defined in claim 10, wherein said locking means includes a dog on one end of a rotatable shaft; a stop for engaging said dog when said diverting element is in diverting position; a pawl connected to said diverting element for pivotal movement therewith, and cooperative camming surfaces on said dog and said pawl, said surfaces when mated being especially adapted to press said dog against said stop and hold said pawl with said diverting member in diverting position.
 12. A switch as defined in claim 4, wherein support means are provided for said sensor, said support means biasing said sensor into raised position above the floor surface and permitting said sensor to be depressed into said floor; a flexible connection in said one shaft permitting the end thereof connected to said sensor element to pivot with respect to the other end thereof.
 13. A switch as defined in claim 12 wherein said flexible connection is between said sensor element and said motion translating means.
 14. A switch as defined in claim 12 wherein said sensor has a pair of guards normally projecting above the floor surface and spaced to form a slot to receive said sensor element; said guards being depressible into the floor with said sensor.
 15. A tow pin directing switch for the two pin guiding channel of a recessed in-floor conveyor at the juncture of a generally U-shaped main track guiding channel and a spur track guiding channel diverging therefrom, said main track having an opening in a side thereof with the juncture of said spur track, said switch comprising: a body element; said body element being shaped in the form of a hollow barrel encompassing said main track at said juncture; means mounting said body element for rocking movement laterally of said main track, said body element having an upwardly opening slot therein extending in the direction of said main track, one side of said slot being at an angle to said main track and converging toward the other side of said slot in the same direction as said guiding channel of said spur track diverges from the guiding channel of said main track, said slot forming a continuation of the guiding channel of said main track when said body element is rocked into one position and said one side of said slot extending across said guiding channel of said main track and the adjacent portion of said slot forming an angular guideway connecting said main and spur track guiding channels when said body element is rocked into the other of its positions.
 16. The tow pin directing switch as defined in claim 15 wherein said body element is pivotally mounted for rocking movement on an axis generally parallel to said main track and said main track passes through said element.
 17. A switch as described in claim 15 wherein a sensor is provided; second means for imparting rocking motion to said element; said sensor being connected to said second means for shifting said element from retracted to extended position.
 18. A switch as described in claim 19 wherein said element is biased into retracted position; a release member connected to said element and shifted into retracted position; a release member connected to said element and shifted into truck pin engaging position in the truck pin slot of said spur track simultaneously with the shifting of said element to extended position and a stop member locking said element in extended position; said stop member connected to said release member and shifting said stop member to non-locking position when said release member is engaged by a truck pin. 